Chad Pecknold, associate professor, theology, was on CNBC's Squawk Box commenting on the Pope's comments on Donald Trump and Christianity. Kenneth Pennington, Kelly-Quinn Professor of Ecclesiastical and Legal History, spoke to the New York Times on Vatican City walls. John Kenneth White, professor, politics, published an op-ed in the New York Daily News. See below.

Catholics and the GOP: It’s complicated. What Trump's skirmish with the Pope says about the future of this important constitutency

The spat between Pope Francis and Donald Trump is just the latest twist in a Republican presidential race that has already seen its fair share of surprises. Not surprisingly, the Pope's comment that Trump cannot be Christian since Christians build bridges-not walls-elicited a furious response. Trump called the Pope's statement "disgraceful," adding that the Vatican is in the crosshairs of ISIS, and charging that Francis is a "pawn" of the Mexican government.

But what surprised me especially as a scholar of religion and politics was the reaction of the other Republican contenders, who found themselves agreeing with Trump against a beloved figure. Marco Rubio argued that while the U.S. is "compassionate," the nation has "an obligation to control the process by which people enter the United States." Jeb Bush said it "only enables bad behavior when someone from outside our country talks about Donald Trump."

In Defense of Trump, Some Point (Wrongly) to Vatican Walls

... Gaining access to some parts of the Vatican, such as the library or the archives, is more complicated than just strolling into St. Peter’s Square. But the process does not appear to be too cumbersome.

Ken Pennington, a professor of medieval history at the Catholic University of America, in Washington, said his research on canon law had brought him into the Vatican many times over the past four decades.

Visitors must show some form of identification to a guard and explain the purpose of their visit, he said, but if they have a library card from the Vatican Library, they can use that to gain entry, too.

“When I am there I show the guards my library card and they let me right in,” he said. “It’s the only place in the world where a library card gets you into a country.” ...